Illuminating appliances designed for
post mounting shall be securely and rigidly attached to a post.
Posts shall be rigidly mounted. The strength and rigidity of posts
exceeding 3 feet (914 mm) in height shall be not less than a 21/2
inch (64 mm) diameter post constructed of 0.064 of an inch
(1.626 mm) thick steel or a 1 inch (25.4 mm) Schedule 40 steel
pipe. Posts 3 feet (914 mm) or less in height shall not be smaller
than a 3/4 of an inch (19.1 mm) Schedule 40 steel pipe. Drain
openings shall be provided near the base of posts where there is
a possibility of water collecting inside them. [NFPA 54:10.16.4]